More suggestions.

[Threefinger]

1. Relate captors value to the slave trader off of his level.

River pirate 50g.
Knight 500g.

Everying else scaled in between.

2. Incorporate different formations. Follow me just groups all your troups around you. So much so that you can't shoot your crossbow/bow without hitting one of them.

 

[RJii]

1. Relate captors value to the slave trader off of his level.

River pirate 50g.
Knight 500g.

Everying else scaled in between.

Why? If you think about it, the slave trader is the one paying for these slaves. And he wants them to work for him (if I've undestud correctly), atleast the one at the salt mines does. So, is the knight going to work 10x more than a river pirate? If so, then yes, he should pay ten times in denars.

 

[Corto]

Maybe there could be some other way to ransom the noble prisoners (ie. knights or special npcs), in case such a valuable captive falls in players hands?

A possibility to sell swadian/vaergir noble prisoner to the enemy or ransom them to their own people sound a good side quest on its own. Practically it would be "save the girl" quest reversed: player is the kidnapper, and the ransom payers wait in a location for the trade. They might pay or attack the player depending on the size and quality of each group's forces.

 

[ruoste]

well, you dont see nobles if you are not on a quest to kidnap one.
that kind of quest you suggest is already in the game.

 

[Threefinger]

My point with the prisoner values is just that its not worth trying to take knights and such prisoner. To much risk for no reward. May as well just kill river pirates all day.

 

[Thucydides]

Already suggested. Good ideas, of course, but old news.